The austenitic stainless steels such as AISI 310 and cast nickel-based supper alloys such as Inconel 657 are of engineering materials that are used widely in high temperature components of Oil-Refinery industries. To perform dissimilar joining between AISI 310 SS and Inconel 657 supperalloy, fusion joining should be used. The current investigation is discussed about cases such as weldability, base metals microstructure, welds microstructure (weld metals, heat-affected zones, interfaces and partially melted zones) and mechanical properties of dissimilar welds between AISI 310 SS and Inconel 657 superalloy in order to select the best filler material(s). Because this joint should stand at 1000±50 ?C of work condition, therefore joint microstructure and mechanical properties also investigated after the aging treatment. The experimental researches showed that the size of unmixed zone in the 310 SS base metal side is wider than of Inconel 657 base metal side. The grain growth has occurred only in the HAZ of 310 SS base metal, whereas the partially melted zone is formed only in the HAZ of Inconel 657 base metal. The microhardness measurements exhibited that the highest and lowest hardness values have been seen in Inconel A and 310 SS weld metals, respectively. Also, the result of tension tests for the age weldments showed that the failure occurred at the weld metal (for Inconel 617 and 310 SS weld metals) or at 310 SS base metal (for Inconel A and Inconel 82 weld metals). The impact energy values for aged Inconel 617 and 310 SS weld metals showed high decreasing, where can be attributed to the severe precipitation and weak thermal stability of these weld metals. The Varestraint weldability test for the weld metals exhibited that Inconel A weld metal has the best resistance to hot cracking. At last it can be concluded that Inconel A and Inconel 82 weld metals are the best compromise, respectively for the dissimilar weld between AISI 310 SS and Inconel 657 superalloy.